FIELD OF THE INVENTION
The invention relates to an apparatus for introducing feed water into a steam generator, preferably into a waste-heat boiler of a combined-cycle power station having at least one waste-heat boiler, including a high-pressure system and a low-pressure system to be respectively fed from at least one feed-water container and having feed-water pump lines being respectively configured so as to be triply redundant, the feed-water pump lines having pumps with an electrical drive motor.
In order to provide steam as the driving medium for steam turbines, it is generally known to introduce feed water into a steam generator in which the feed water is evaporated and, if appropriate, superheated. It is then supplied to the relevant steam turbine. In order to introduce the feed water, it is also known to provide pumps which deliver the feed water from a feed-water container or comparable feed-water reservoir.
In a power station block of a combined-cycle installation, as a rule at least two waste-heat boilers which are supplied with feed water in the specified manner are provided. It is then usual to configure the waste-heat boilers as so-called two-pressure waste-heat boilers, i.e. boilers with pipeline systems at different pressure levels. Those pipeline systems are correspondingly continued in the waste-heat boiler by the evaporators and superheaters installed therein.
As in other power station installations, the introduction of the feed water in such a two-pressure waste-heat boiler takes place with triple redundancy for each pressure system, i.e. by employing three mutually independent pumps. Each pump is then usually constructed for 50% of the maximum delivery output so that one pump unit is held in reserve in each case if another unit should fail.
So-called medium-voltage motors are provided as the motorized drives for the high-pressure pumps to suit the different pressure stages, namely high pressure at approximately 120 bar and low pressure at approximately 16 bar, whereas the low-pressure pumps are driven by low-voltage motors which have a relatively unfavorable efficiency as compared with the medium-voltage motors.